Imaging element, method of manufacturing imaging element, imaging device, and method of manufacturing imaging device

ABSTRACT

There is provided a method of manufacturing an imaging device including a plurality of imaging elements in an imaging area, where each imaging element includes a photoelectric conversion unit in a substrate and a wire grid polarizer arranged at a light-incident side of the photoelectric conversion unit. The method generally includes forming the wire grid polarizer that includes a plurality of stacked strip-shaped portions, where each of the plurality of stacked strip-shaped portions includes a portion of a light-reflecting layer and a portion of a light-absorbing layer. The light-reflecting layer may include a first electrical conducting material that is electrically connected to at least one of the substrate or the photoelectric conversion unit. The light-absorbing layer may include a second electrical conducting material, where at least a portion of the light-absorbing layer is in contact with the light-reflecting layer.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.15/766,587 filed Apr. 6, 2018, which is a national stage applicationunder 35 U.S.C. 371 and claims the benefit of PCT Application No.PCT/JP2016/004434 having an international filing date of Sep. 30, 2016,which designated the United States, which PCT application claimed thebenefit of Japanese Priority Patent Application JP 2015-202659 filedOct. 14, 2015, the entire disclosures of each of which are incorporatedherein by reference.

TECHNICAL FIELD

The present disclosure relates to imaging elements, methods ofmanufacturing the imaging element, imaging devices, and methods ofmanufacturing the imaging device.

BACKGROUND ART

For example, according to JP2012-238632A, an imaging device having aplurality of imaging elements with wire grid polarizers (WGPs) is wellknown. For example, a photoelectric conversion area includes acharge-coupled device (CCD) or a complementary metal-oxide-semiconductor(CMOS) image sensor. The photoelectric conversion area is included in aphotoelectric conversion unit in the imaging element and generatescurrent on the basis of incident light. The wire grid polarizer isarranged at a light-incident side of the photoelectric conversion unit.For example, in the wire grid polarizer, a plurality of band-likelight-reflecting layers, insulating layers, and light-absorbing layersare separately placed side by side. The light-absorbing layer made of asecond electrical conducting material is positioned at thelight-incident side, and the light-reflecting layer made of a firstelectrical conducting material is positioned at the photoelectricconversion unit side.

As illustrated in a conceptual diagram in FIG. 25, a wire gridselectively reflects/absorbs electromagnetic waves oscillating atsurfaces parallel to a wire grid extending direction in a case where apitch P₀ at which the wire grid has been formed is significantly smallerthan an effective wavelength of the incident electromagnetic waves.Therefore, as illustrated in FIG. 25, although the electromagneticwaves, before reaching the wire grid polarizer, include a verticalpolarization component and a horizontal polarization component, thevertical polarization component becomes a dominant linear polarizationin the electromagnetic waves passed through the wire grid polarizer.When focusing on a visible light wavelength band, a surface of the wiregrid reflects or absorbs a polarization component biased toward asurface parallel to the wire grid extending direction in the case wherethe pitch P₀ at which the wire grid has been formed is significantlysmaller than the effective wavelength of the electromagnetic wavesincident on the wire grid polarizer. On the other hand, when anelectromagnetic wave having a polarization component biased toward asurface perpendicular to the wire grid extending direction enters thewire grid, an electric field propagates a front surface of the wiregrid, and the electric field having the same wavelength and the samepolarization orientation as the incident wavelength exits from a rearsurface of the wire grid.

CITATION LIST Patent Literature

[PTL 1]

JP 2012-238632A

SUMMARY Technical Problem

In manufacturing the wire grid polarizer, a light-reflectinglayer-forming layer made of a first electrical conducting material, aninsulating layer, and a light-absorbing layer-forming layer made of asecond electrical conducting material are formed in this order on aphotoelectric conversion unit, and subsequently the light-reflectinglayer-forming layer, the insulating layer, and the light-absorbinglayer-forming layer are etched. When such a wire grid polarizer ismanufactured, the light-reflecting layer-forming layer and thelight-absorbing layer-forming layer are in a floating state (state inwhich layers are not electrically connected anywhere). Therefore, duringfilm formation or an etching process, the light-reflecting layer-forminglayer or the light-absorbing layer-forming layer may be charged and akind of discharge may occur. Unfortunately, the wire grid polarizer andthe photoelectric conversion unit may be damaged. For example, in thetechnology disclosed in JP 2012-238632A, a wire grid polarizer is formedand then a conductive layer is formed on all surfaces of the wire gridpolarizer. Therefore, it is difficult to prevent a light-reflectinglayer-forming layer or a light-absorbing layer-forming layer from beingcharged during film formation or an etching process. In the technologydisclosed in JP 2012-238632A, formation of a conductive layer preventselectrostatic dust and so on from adhering after forming the wire gridpolarizer in an imaging device. The adhesion of the electrostatic dustand so on is liable to occur before the imaging device is sealed by atransparent lid member in a packaging process.

Therefore, embodiments of the present disclosure provide an imagingelement, a method of manufacturing the imaging element, an imagingdevice, and a method of manufacturing the imaging device that havestructures or configurations capable of suppressing discharge duringmanufacturing a wire grid polarizer.

Solution to Problem

According to an embodiment of the present disclosure, there is provideda method of manufacturing an imaging device including a plurality ofimaging elements in an imaging area,

each of the imaging elements including

a photoelectric conversion unit on a substrate, and

a wire grid polarizer which is arranged at a light-incident side of thephotoelectric conversion unit and in which a plurality of stackedstructures are separately placed side by side, each of the stackedstructures including at least a band-like light-reflecting layer and aband-like light-absorbing layer,

the method including:

manufacturing each of the imaging elements by

(a) forming a light-reflecting layer-forming layer made of a firstelectrical conducting material on the photoelectric conversion unitafter forming the photoelectric conversion unit,

(b) next, on or above the light-reflecting layer-forming layer, forminga light-absorbing layer-forming layer which is made of a secondelectrical conducting material and at least a part of which is incontact with the light-reflecting layer-forming layer, and

(c) subsequently, patterning the light-absorbing layer-forming layer andthe light-reflecting layer-forming layer to obtain the wire gridpolarizer in which the plurality of stacked structures are separatelyplaced side by side, each of the stacked structures including theband-like light-reflecting layer and the band-like light-absorbinglayer. In (a), the light-reflecting layer-forming layer made of thefirst electrical conducting material is electrically connected to thesubstrate or the photoelectric conversion unit.

According to an embodiment of the present disclosure, there is provideda method of manufacturing an imaging element including

a photoelectric conversion unit on a substrate, and

a wire grid polarizer which is arranged at a light-incident side of thephotoelectric conversion unit and in which a plurality of stackedstructures are separately placed side by side, each of the stackedstructures including at least a band-like light-reflecting layer and aband-like light-absorbing layer,

the method including:

(A) after forming the photoelectric conversion unit, forming alight-reflecting layer-forming layer which is made of a first electricalconducting material and which is electrically connected to the substrateor the photoelectric conversion unit, on the photoelectric conversionunit;

(B) next, on or above the light-reflecting layer-forming layer, forminga light-absorbing layer-forming layer which is made of a secondelectrical conducting material and at least a part of which is incontact with the light-reflecting layer-forming layer; and

(C) subsequently, patterning the light-absorbing layer-forming layer andthe light-reflecting layer-forming layer to obtain the wire gridpolarizer in which the plurality of stacked structures are separatelyplaced side by side, each of the stacked structures including theband-like light-reflecting layer and the band-like light-absorbinglayer.

According to an embodiment of the present disclosure, there is providedan imaging device including

a plurality of imaging elements in an imaging area,

each of the imaging elements including

a photoelectric conversion unit on a substrate, and

a wire grid polarizer which is arranged at a light-incident side of thephotoelectric conversion unit and in which a plurality of stackedstructures are separately placed side by side, each of the stackedstructures including at least a band-like light-reflecting layer and aband-like light-absorbing layer.

The light-reflecting layer is made of a first electrical conductingmaterial,

the light-absorbing layer is made of a second electrical conductingmaterial, and

an extending part of the light-reflecting layer is electricallyconnected to the substrate or the photoelectric conversion unit.

According to an embodiment of the present disclosure, there is providedan imaging element including:

a photoelectric conversion unit on a substrate; and

a wire grid polarizer which is arranged at a light-incident side of thephotoelectric conversion unit and in which a plurality of stackedstructures are separately placed side by side, each of the stackedstructures including at least a band-like light-reflecting layer and aband-like light-absorbing layer.

The light-reflecting layer is made of a first electrical conductingmaterial,

the light-absorbing layer is made of a second electrical conductingmaterial, and an extending part of the light-reflecting layer iselectrically connected to the substrate or the photoelectric conversionunit.

According to an embodiment of the present disclosure, there is provideda method of manufacturing an imaging device including a plurality ofimaging elements in an imaging area, each imaging element including aphotoelectric conversion unit in a substrate and a wire grid polarizerarranged at a light-incident side of the photoelectric conversion unit,the method including: forming the photoelectric conversion unit in thesubstrate; forming a light-reflecting layer on or above thephotoelectric conversion unit, wherein the light-reflecting layerincludes a first electrical conducting material that is electricallyconnected to at least one of the substrate or the photoelectricconversion unit; forming a light-absorbing layer on or above thelight-reflecting layer, wherein the light-absorbing layer includes asecond electrical conducting material, and wherein at least a portion ofthe light-absorbing layer is in contact with the light-reflecting layer;and patterning the light-absorbing layer and the light-reflecting layerto form a wire grid polarizer including a plurality of stackedstrip-shaped portions, wherein each of the plurality of stackedstrip-shaped portions includes a portion of the light-reflecting layerand a portion of the light-absorbing layer.

According to an embodiment of the present disclosure, there is providedan imaging element including: a photoelectric conversion unit in asubstrate; a wire grid polarizer disposed at a light-incident side ofthe photoelectric conversion unit, the wire grid polarizer including aplurality of stacked strip-shaped portions, each stacked strip-shapedportion including a light-reflecting layer and a light-absorbing layer;and an extending portion of the light-reflecting layer electricallyconnected to the substrate or the photoelectric conversion unit,wherein, the light-reflecting layer includes a first electricalconducting material, and the light-absorbing layer includes a secondelectrical conducting material.

According to an embodiment of the present disclosure, there is providedanimaging device including: a plurality of imaging elements in animaging area, each imaging element including: a photoelectric conversionunit in a substrate; a wire grid polarizer disposed at a light-incidentside of the photoelectric conversion unit, the wire grid polarizerincluding a plurality of stacked strip-shaped portions, each stackedstrip-shaped portion including a light-reflecting layer and alight-absorbing layer; and an extending portion of the light-reflectinglayer electrically connected to the substrate or the photoelectricconversion unit, wherein, the light-reflecting layer includes a firstelectrical conducting material, and the light-absorbing layer includes asecond electrical conducting material.

Advantageous Effects of Invention

In the imaging element obtained by the method of manufacturing animaging element according to embodiments of the present disclosure, theimaging element obtained by the method of manufacturing an imagingdevice according to the embodiments of the present disclosure, theimaging element according to the embodiments of the present disclosure,and the imaging element included in the imaging device according to theembodiments of the present disclosure, the light-reflectinglayer-forming layer is electrically connected to the substrate or thephotoelectric conversion unit, the light-reflecting layer-forming layerelectrically connected to the substrate or the photoelectric conversionunit is prepared, and the extending part of the light-reflecting layeris electrically connected to the substrate or the photoelectricconversion unit. Therefore, during formation of the wire grid polarizer,it is certainly possible to prevent the wire grid polarizer and thephotoelectric conversion unit from being damaged after light-reflectinglayer-forming layer or the light-absorbing layer-forming layer ischarged and a kind of discharge occurs. The effects described in thisspecification are just examples and are not limitations. There may beadditional effects.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic partial end view of imaging elements in an imagingdevice according to a first embodiment.

FIG. 2 is a schematic partial end view of imaging elements in an imagingdevice according to the first embodiment.

FIG. 3 is a schematic partial plan view of imaging elements in animaging device according to the first embodiment.

FIG. 4 is a schematic partial plan view of imaging elements in animaging device according to the first embodiment.

FIG. 5 is a schematic perspective view of a wire grid polarizerconstituting an imaging element in an imaging device according to thefirst embodiment.

FIG. 6 is a schematic plan view of an imaging device illustrating animaging area and the like in the imaging device according to the firstembodiment.

FIG. 7A is a schematic partial end view of a substrate and the like thatillustrates a method of manufacturing an imaging element and an imagingdevice according to the first embodiment.

FIG. 7B is a schematic partial end view of a substrate and the like thatillustrates a method of manufacturing an imaging element and an imagingdevice according to the first embodiment.

FIG. 7C is a schematic partial end view of a substrate and the like thatillustrates a method of manufacturing an imaging element and an imagingdevice according to the first embodiment.

FIG. 7D is a schematic partial end view of a substrate and the like thatillustrates a method of manufacturing an imaging element and an imagingdevice according to the first embodiment.

FIG. 8 is a schematic partial end view of imaging elements in an imagingdevice according to a second embodiment.

FIG. 9 is a schematic partial end view of imaging elements in an imagingdevice according to the second embodiment.

FIG. 10 is a conceptual diagram of imaging element units having theBayer arrangement in an imaging device according to the firstembodiment.

FIG. 11 is a conceptual diagram of a modification of imaging elementunits having the Bayer arrangement in an imaging device according to thefirst embodiment or the second embodiment.

FIG. 12 is a conceptual diagram of a modification of imaging elementunitshaving the Bayer arrangement in an imaging device according to thefirst embodiment or the second embodiment.

FIG. 13 is a conceptual diagram of a modification of imaging elementunits having the Bayer arrangement in an imaging device according to thefirst embodiment or the second embodiment.

FIG. 14 is a conceptual diagram of a modification of imaging elementunits having the Bayer arrangement in an imaging device according to thefirst embodiment or the second embodiment.

FIG. 15 is a conceptual diagram of a modification of imaging elementunits having the Bayer arrangement in an imaging device according to thefirst embodiment or the second embodiment.

FIG. 16 is a conceptual diagram of a modification of imaging elementunits having the Bayer arrangement in an imaging device according to thefirst embodiment or the second embodiment.

FIG. 17 is a conceptual diagram of a modification of imaging elementunits having the Bayer arrangement in an imaging device according to thefirst embodiment or the second embodiment.

FIG. 18 is a conceptual diagram of a modification of imaging elementunits having the Bayer arrangement in an imaging device according to thefirst embodiment or the second embodiment.

FIG. 19 is a conceptual diagram of a modification of imaging elementunits having the Bayer arrangement in an imaging device according to thefirst embodiment or the second embodiment.

FIG. 20 is a conceptual diagram of a modification of imaging elementunits having the Bayer arrangement in an imaging device according to thefirst embodiment or the second embodiment.

FIG. 21 is a conceptual diagram of a modification of imaging elementunits having the Bayer arrangement in an imaging device according to thefirst embodiment or the second embodiment.

FIG. 22 is a conceptual diagram of a modification of imaging elementunits having the Bayer arrangement in an imaging device according to thefirst embodiment or the second embodiment.

FIG. 23 is a conceptual diagram of a modification of imaging elementunits having the Bayer arrangement in an imaging device according to thefirst embodiment or the second embodiment.

FIG. 24 is a conceptual diagram of a modification of imaging elementunits having the Bayer arrangement in an imaging device according to thefirst embodiment or the second embodiment.

FIG. 25 is a conceptual diagram illustrating light and the like passingthrough a wire grid polarizer.

DESCRIPTION OF EMBODIMENTS

Hereinafter, with reference to the drawings, the present disclosure willbe described based on embodiments, which are not intended to limit thepresent disclosure and in which different values and materials are byway of example only. Note that the description is given in the followingorder.

1. General description of imaging element, method of manufacturingimaging element, imaging device, and method of manufacturing imagingdevice according to embodiments of the present disclosure

2. First embodiment (imaging element, method of manufacturing imagingelement, imaging device, and method of manufacturing imaging deviceaccording to embodiment of present disclosure (imaging element Aaccording to embodiment of present disclosure))

3. Second embodiment (modification of first embodiment (imaging elementB according to embodiment of present disclosure))

4. Other Case

<General Description of Imaging Element, Method of Manufacturing ImagingElement, Imaging Device, and Method of Manufacturing Imaging DeviceAccording to Embodiments of Present Disclosure>

In an imaging device and an imaging element obtained by a method ofmanufacturing the imaging device according to the embodiments of thepresent disclosure, a light-reflecting layer and a light-absorbing layermay be shared by the imaging elements.

According to the method of manufacturing an imaging device in theembodiments of the present disclosure including a preferable embodiment,

in the step (b), the light-absorbing layer-forming layer made of thesecond electrical conducting material can be formed on or above thelight-reflecting layer-forming layer in a state in which potential ofthe light-reflecting layer-forming layer is set to a predeterminedpotential via the substrate or the photoelectric conversion unit, and

in the step (c), the light-absorbing layer-forming layer and thelight-reflecting layer-forming layer can be patterned in a state inwhich the potential of the light-reflecting layer-forming layer is setto a predetermined potential via the substrate or the photoelectricconversion unit.

In addition, according to the method of manufacturing an imaging elementin the embodiments of the present disclosure including a preferableembodiment,

in the step (B), the light-absorbing layer-forming layer made of thesecond electrical conducting material can be formed on or above thelight-reflecting layer-forming layer in a state in which potential ofthe light-reflecting layer-forming layer is set to a predeterminedpotential via the substrate or the photoelectric conversion unit, and

in the step (C), the light-absorbing layer-forming layer and thelight-reflecting layer-forming layer can be patterned in a state inwhich the potential of the light-reflecting layer-forming layer is setto a predetermined potential via the substrate or the photoelectricconversion unit.

In the method of manufacturing an imaging device according to theembodiments of the present disclosure including a preferable embodiment,an area in which the substrate or the photoelectric conversion unit iselectrically connected to the light-reflecting layer-forming layer maybe positioned in an imaging area, may be positioned in an optical blackpixel area (OPB) at an outer circumference of the imaging area, or maybe positioned in a peripheral area outside the imaging area. In theimaging device according to the embodiments of the present disclosure,an area in which the extending part of the light-reflecting layer iselectrically connected to the substrate or the photoelectric conversionunit may be positioned in the imaging area, may be positioned in theoptical black pixel area (OPB) at the outer circumference of the imagingarea, or may be positioned in the peripheral area outside the imagingarea. In the case where the area, in which the substrate or thephotoelectric conversion unit is electrically connected to thelight-reflecting layer-forming layer, is positioned in the imaging areaor in the optical black pixel area (OPB), the area may be provided ineach imaging element. Alternatively, the area may be provided for aplurality of imaging elements, or for all the imaging elements.Alternatively, the area may be for one imaging element, or a pluralityof the areas may be provided for one imaging element. In the case wherethe area is positioned in the peripheral area, one or a plurality of theareas may be provided.

The wire grid polarizer does not have to be formed in the peripheralarea or in an area between the imaging elements. The peripheral area orthe area between the imaging elements (including an imaging elementpositioned in the optical black pixel area, and the same applies to thefollowing) are preferably occupied by a second stacked structure (frame)including at least the light-reflecting layer and the light-absorbinglayer (for example, including light-reflecting layer, insulating layer,and light-absorbing layer). In the case where the second stackedstructure does not function as the wire grid polarizer, a line and spacepattern may be provided like the wire grid polarizer. In other words,the pitch P₀ at which the wire grid has been formed may be sufficientlylarger than the effective wavelength of incident electromagnetic waves.

A light-blocking layer can be formed in the area between the imagingelements, and the extending part of the light-reflecting layer can be incontact with the area of the light-blocking layer. The length of theextending part of the light-reflecting layer in contact with the area ofthe light-blocking layer can be the same length as a photoelectricconversion area that is an area in the imaging element for substantiallycarrying out the photoelectric conversion. Alternatively, the length ofthe extending part can be the same length as the photoelectricconversion area or can be the length equal to half of the length of thephotoelectric conversion area. Such configurations can prevent colormixture from neighboring imaging elements. The area in which thelight-reflecting layer-forming layer is in contact with thelight-absorbing layer-forming layer is the area between the imagingelements, and can be one of the four corners of the imaging element. Thelight-blocking layer can also be formed in the peripheral area, and theextending part of the light-reflecting layer can be in contact with thearea of the light blocking layer. The length of the extending part ofthe light-reflecting layer in contact with the area of thelight-blocking layer can be an arbitrary length inherently.

In the imaging device, the method of manufacturing an imaging device,the imaging element, and the method of manufacturing an imaging elementaccording to the embodiments of the present disclosure includingpreferable embodiments, the wire grid polarizer can include thelight-reflecting layer, the insulating layer, and the light-absorbinglayer that are stacked in this order from the photoelectric conversionunit side. In this case, the insulating layer can be formed on a wholetop surface of the light-reflecting layer, and the light-absorbing layercan be formed on a whole top surface of the insulating layer. Thisenables the whole area of the light-absorbing layer and thelight-reflecting layer to be electrically connected to the substrate orthe photoelectric conversion unit, and it is possible to preventdischarge more certainly. Alternatively, the wire grid polarizer caninclude the light-reflecting layer and the light-absorbing layer thatare stacked in this order from the photoelectric conversion unit sidewhile the insulating layer is omitted. In this case, a base film can beformed between the photoelectric conversion unit and thelight-reflecting layer. This enables roughness of the light-reflectinglayer-forming layer and the light-reflecting layer to be improved.

In the imaging element, the imaging element constituting the imagingdevice, the imaging element obtained by the method of manufacturing animaging element, the imaging element obtained by the method ofmanufacturing an imaging device according to embodiments of the presentdisclosure including the preferable embodiments described above(hereinafter, these imaging elements may be referred to as “imagingelements and(or) the like according to the embodiments of the presentdisclosure”), the direction in which the band-like light-reflectinglayer extends is the same as a polarization orientation in which lightis extinguished, and the repeating direction of the band-likelight-reflecting layer is the same as a polarization orientation inwhich light penetrates. In other words, the light-reflecting layer has afunction of a polarizer. Among light incident on the wire gridpolarizer, the light-reflecting layer attenuates polarized waves (one ofTE waves/S waves and TM waves/P waves) having an electric fieldcomponent in a direction parallel to the direction in which thelight-reflecting layer extends, and the light-reflecting layer transmitspolarized waves (the other of TE waves/S waves and TM waves/P waves)having an electric field component in a direction perpendicular to thedirection in which the light-reflecting layer extends (repeatingdirection of band-like light-reflecting layer). That is, the directionin which the light-reflecting layer extends is a light-absorbing axis ofthe wire grid polarizer, and the direction perpendicular to thedirection in which the light-reflecting layer extends is a lighttransmission axis of the wire grid polarizer. For convenience, sometimesthe direction in which the band-like light-reflecting layer (having theline and space pattern) extends may be referred to as a “firstdirection”, and the repeating direction of the band-likelight-reflecting layer (direction perpendicular to a direction in whichthe light-reflecting layer extends) may be referred to as a “seconddirection.”

In the imaging element or the like according to an embodiment of thepresent disclosure, the length of the light-reflecting layer in thefirst direction can be the same length as the length of thephotoelectric conversion area in the first direction, the same length asthe length of the imaging element, or the integer multiple of the lengthof the imaging element in the first direction. The photoelectricconversion area is the area in which photoelectric conversion issubstantially carried out in the imaging element.

With regard to the imaging elements or the like according to embodimentsof the present disclosure, imaging elements having an angle of 0 degreebetween the first direction and a direction, in which a plurality ofimaging elements are arranged, and imaging elements having an angle of90 degrees between the first direction and the direction, in which aplurality of imaging elements are arranged, can be combined.Alternatively, imaging elements having an angle of 0 degree, imagingelements having an angle of 45 degrees, imaging elements having an angleof 90 degrees, and imaging elements having an angle of 135 degreesbetween the first direction and the direction, in which a plurality ofimaging elements are arranged, can be combined, for example.

With regard to the imaging element or the like according to embodimentsof the present disclosure, the wire grid polarizer can be disposed overan on-chip lens (OCL), or the on-chip lens (OCL) can be disposed overthe wire grid polarizer. For convenience, the former imaging element isreferred to as an “imaging element A according to an embodiment of thepresent disclosure,” and the latter imaging element is referred to as an“imaging element B according to an embodiment of the presentdisclosure.”

In the imaging element A according to the embodiment of the presentdisclosure, a planarizing layer and a base insulating layer can beformed in this order between the on-chip lens (positioned at lower side)and the wire grid polarizer (positioned at upper side) from the on-chiplens side. For example, the planarizing layer is made of transparentresin (for example, acrylic resin), and the base insulating layer ismade of inorganic material such as a silicone oxide film that functionsas a base of a process in a step for manufacturing the wire gridpolarizer. In addition, in the imaging element A according to theembodiment of the present disclosure having the above-describedpreferable structure, a wavelength selection layer (specifically, forexample, a known color filter layer) can be disposed below the on-chiplens.

On the other hand, in the imaging element B according to an embodimentof the present disclosure, a wavelength selection layer (specifically,for example, a known color filter layer) can be disposed between thewire grid polarizer (positioned at lower side) and the on-chip lens(positioned at upper side). By adopting such a configuration, it ispossible to optimize each wire grid polarizer independently in awavelength band of transmitted light in each wire grid polarizer, and itis also possible to achieve a lower reflectance ratio in all visiblelight areas. The planarizing layer is in between the wire grid polarizerand the wavelength selection layer, and the base insulating layer isformed below the wire grid polarizer. The base insulating layer is madeof inorganic material such as a silicone oxide film that functions as abase of a process in a step for manufacturing the wire grid polarizer.

The example of the color filter layer includes a filter layer thattransmits a specific wavelength such as red, green, blue, cyan, magenta,or yellow. The color filter layer can include an organic color filterlayer using an organic compound such as pigment or dye, or can include awavelength selector using photonic crystal or plasmon (color filterlater having a conductor grid structure in which a conductor's thin filmhas a grid-like hole structure. For example, JP 2008-177191A), or a thinfilm made of an inorganic material such as amorphous silicon.

In addition, with regard to the imaging element or the like according tothe embodiment of the present disclosure, a light-blocking layer is inan area positioned between adjacent imaging elements. The light-blockinglayer is made of chromium (Cr), copper (Cu), aluminum (Al), or tungsten(W), for example. This enables leakage of light into adjacent imagingelements (polarization crosstalk) to be prevented more effectively. Inaddition, various kinds of wiring (wiring layer) made of aluminum (Al),copper (Cu), or the like is in the photoelectric conversion unit todrive the imaging element.

The example of the substrate includes a compound semiconductor substratesuch as an InGaAs substrate and a silicon semiconductor substrate.

In the imaging element A according to the embodiment of the presentdisclosure, the photoelectric conversion unit includes the photoelectricconversion area, the on-chip lens, the planarizing layer, the baseinsulating layer, the light-blocking layer, the color filter layer, thewiring (wiring layer), and various interlayer insulating layers. In thephotoelectric conversion area, current is generated on the basis ofincident light. In the imaging element B according to the embodiment ofthe present disclosure, the photoelectric conversion unit includes thephotoelectric conversion area, the base insulating layer, thelight-blocking layer, the wiring (wiring layer), and various interlayerinsulating layers. In the photoelectric conversion area, current isgenerated on the basis of incident light. For example, a part of thephotoelectric conversion unit that is electrically connected to theextending part of the light-reflecting layer and the light-reflectinglayer-forming layer is the light-blocking layer or the wiring (wiringlayer). For example, in a part of the substrate that is electricallyconnected to the extending part of the light-reflecting layer and thelight-reflecting layer-forming layer, a concentrated impurity area, ametal later, an alloy layer, the wiring layer or the like may be formed.

In the imaging element or the like of the embodiments of the presentdisclosure, the light-reflecting layer may be made of metal material,alloy material, or semiconductor material, and the light-absorbing layermay be made of metal material, alloy material, or semiconductormaterial.

Examples of the inorganic material constituting the light-reflectinglayer (light-reflecting layer-forming layer) include metal materialssuch as aluminum (Al), silver (Ag), gold (Au), copper (Cu), platinum(Pt), molybdenum (Mo), chromium (Cr), titanium (Ti), nickel (Ni),tungsten (W), iron (Fe), silicon (Si), germanium (Ge), or tellurium(Te), alloy material including such metal, and semiconductor material.Examples of material constituting the base film (barrier metal layer)between the photoelectric conversion unit and the light-reflecting layerinclude Ti, TiN, and a stacked structure of Ti/TiN.

Examples of material constituting the light-absorbing layer(light-absorbing layer-forming layer) include metal material, alloymaterial, and semiconductor material whose extinction coefficients k arenot zero; in other words, they have a light-absorbing function.Specifically, the examples include metal material such as aluminum (Al),silver (Ag), gold (Au), copper (Cu), molybdenum (Mo), chromium (Cr),titanium (Ti), nickel (Ni), tungsten (W), iron (Fe), silicon (Si),germanium (Ge), tellurium (Te), or tin (Sn), alloy material includingsuch metal, and semiconductor material. In addition, the examplesfurther include silicide-based material such as FeSi₂ (specifically,β-FeSi₂), MgSi₂, NiSi₂, BaSi₂, CrSi₂, or CoSi₂. Specifically, usage ofaluminum, aluminum alloy, or semiconductor material including β-FeSi₂,germanium, or tellurium as the material constituting the light-absorbinglayer enables high contrast (high extinction ratio) in the visible lightarea. In order to attach a polarization characteristic to a wavelengthband other than visible light such as an infrared area, it is preferableto use silver (Ag), copper (Cu), gold (Au), or the like as the materialconstituting the light-absorbing layer (light-absorbing layer-forminglayer). This is because resonant wavelength of such metal is near theinfrared area.

The light-reflecting layer-forming layer and the light-absorbinglayer-forming layer can be formed on the basis of a known method such asvarious chemical vapor deposition methods (CVD methods), coatingmethods, various physical vapor deposition methods (PVD methods)including sputtering and vacuum deposition methods, the sol-gel method,plating methods, the MOCVD method, or the MBE method. Examples of amethod of patterning the light-reflecting layer-forming layer or thelight-absorbing layer-forming layer include a combination of alithography technology and an etching technology (for example, physicaletching technology or an anisotropic dry etching technology using carbontetrafluoride gas, sulfur hexafluoride gas, trifluoromethane gas, orxenon difluoride gas, for example), a so-called liftoff technology, anda so-called self-aligned double patterning technology using a side wallas a mask. Examples of the lithography technology include aphotolithography technology (lithography technology using a light sourcesuch as a g ray and an i ray of a high-pressure mercury vapor lamp, KrFexcimer laser, ArF excimer laser, or EUV, and an immersion lithographytechnology, an electron lithography, and an X-ray lithography thereof).Alternatively, the light-reflecting layer or the light-absorbing layercan be formed on the basis of a nanoimprint method or a microfabricationtechnology using an ultrashort pulse laser such as a femtosecond laser.

Examples of the material constituting the insulating layer (insulatinglayer-forming layer) or the interlayer insulating layer includeinsulating material that is transparent to incident light and that doesnot have a light-absorbing characteristic. Specifically, the examplesinclude SiOx-based material (material constituting silicon-based oxidefilm) such as SiO₂, non-doped silicate glass (NSG), borophosphosilicateglass (BPSG), PSG, BSG, PbSG, AsSG, SbSG, or spin-on glass (SOG), SiN,SiON, SiOC, SiOF, SiCN, low-dielectric constant insulating material (forexample, fluorocarbon, cycloperfluorocarbon polymer, benzocyclobutene,cyclic fluororesin, polytetrafluoroethylene, amorphoustetrafluoroethylene, polyaryl ether, aryl ether fluoride, polyimidefluoride, organic SOG, parylene, fluorinated fullerene, or amorphouscarbon), a polyimide-based resin, a fluorine-based resin, Silk(trademark of The Dow Chemical Co.; a coating-type low-dielectricconstant interlayer insulating film material), and Flare (trademark ofHoneywell Electronic Materials Co.; a polyaryl ether (PAE)-basedmaterial). These materials can be used solely or appropriately incombinations. The insulating layer-forming layer can be formed based onvarious CVD methods, a coating method, various PVD methods including asputtering method and a vacuum evaporation method, various printingmethods such as a screen printing method, and a known method such as asol-gel method. The insulating layer functions as a base layer of thelight-absorbing layer and is formed for the purpose of adjusting thephase of polarized light reflected from the light-absorbing layer andpolarized light having passed through the light-absorbing layer andreflected from the light-reflecting layer and decreasing the reflectanceby an interference effect. Thus, the insulating layer preferably hassuch a thickness that the phase of light after one round trip is shiftedby a half wavelength. Since the light-absorbing layer has alight-absorbing effect, the reflected light is absorbed therein.Therefore, even when the thickness of the insulating layer is notoptimized as described above, it is possible to attain an improvement ofthe extinction ratio. Therefore, the thickness of the insulating layermay be determined based on a balance between practically desiredpolarization characteristics and actual manufacturing steps. Forexample, the thickness of the insulating layer may be in the range of1×10⁻⁹ m to 1×10⁻⁷ m, and more preferably, in the range of 1×10⁻⁸ m to8×10⁻⁸ m. Moreover, the refractive index of the insulating layer may bea value larger than 1.0. Preferably, the refractive index may be set to2.5 or lower, but the refractive index is not limited thereto

In the imaging device according to the embodiments of the presentdisclosure, one imaging element unit (one pixel) is made up of aplurality of imaging elements (subpixels). Each subpixel includes oneimaging element. The relation between pixels and subpixels will bedescribed later.

In the imaging element or the like according to an embodiment of thepresent disclosure, light is incident from the light-absorbing layer.The wire grid polarizer attenuates a polarized wave (one of TE wave/Swave and TM wave/P wave) having an electric field component parallel tothe first direction and transmits a polarized wave (the other of TEwave/S wave and TM wave/P wave) having an electric field componentparallel to the second direction by using four selective light-absorbingactions on the polarized wave based on transmission, reflection,interference, and optical anisotropy of light. That is, one polarizedwave (for example, TE wave) is attenuated by a selective light-absorbingaction on the polarized wave based on the optical anisotropy of thelight-absorbing layer. The band-like light-reflecting layer functions asa polarizer and reflects one of polarized waves (for example, TE wave)that has passed through the light-absorbing layer and the insulatinglayer. In this case, when the insulating layer is configured such thatthe phase of one of the polarized waves (for example, TE wave) that haspassed through the light-absorbing layer and reflected from thelight-reflecting layer is shifted by a half wavelength, one of thepolarized waves (for example, TE wave) reflected from thelight-reflecting layer is cancelled and attenuated by interference withone of polarized waves (for example, TE wave) reflected from thelight-absorbing layer. In this way, it is possible to selectivelyattenuate one polarized wave (for example, TE wave). In this case, asdescribed above, even when the thickness of the insulating layer is notoptimized, it is possible to realize an improvement in the contrast.Therefore, as described above, the thickness of the insulating layer maybe determined on the basis of a balance between practically desiredpolarization characteristics and actual manufacturing steps.

When the metal material or alloy material (hereinafter sometimesreferred to as “metal material or the like”) constituting the wire gridpolarizer meets outside air, corrosion resistance of the metal materialor the like deteriorates due to attachment of moisture or organicmaterials from the outside air. Thus, the long-term reliability of theimaging element may deteriorate. In particular, when moisture adheres ona stacked structure of a metal material or the like, an insulatingmaterial, and a metal material or the like, since CO₂ and O₂ aredissolved in the moisture, it acts as an electrolytic solution. Thus, alocal cell may be formed between two kinds of metals. When such aphenomenon occurs, a reductive reaction such as generation of hydrogenprogresses on a cathode (positive electrode) side, and an oxidativereaction progresses on an anode (negative electrode) side, whereby anabnormal precipitation of the metal material or the like or a change inshape of the wire grid polarizer occurs. As a result, the expectedperformance of the wire grid polarizer and the imaging element may bedegraded. For example, when aluminum (Al) is used for thelight-reflecting layer, an abnormal precipitation of aluminum as shownby the following reaction formula may occur.

Al→Al³⁺+3e⁻Al³⁺+3OH⁻→Al(OH)₃

Therefore, it is preferable that a protective film is formed on the wiregrid polarizer in the imaging element or the like according to theembodiments of the present disclosure. The thickness of the protectivefilm may be in a range such that polarization characteristics are notaffected. Moreover, since the reflectance to incident light is changeddepending on an optical thickness (refractive index×protective filmthickness) of the protective film, the material and thickness of theprotective film may be selected in view of the above. The thickness ofthe protective film may be 15 nm or smaller. Alternatively, thethickness of the protective film may be ¼ or less of the distancebetween the stacked structures. As the material constituting theprotective film, a material of which the refractive index is 2 orsmaller and the extinction coefficient is close to zero is preferred.Examples of the material include insulating material, such as SiO₂including TEOS-SiO₂, SiON, SiN, SiC, SiOC, or SiCN and metal oxide suchas aluminum oxide (AlO_(X)), hafnium oxide (HfO_(x)), zirconium oxide(ZrO_(x)), or tantalum oxide (TaO_(x)). Alternatively, perfluorodecyltrichlorosilane or octadecyl trichlorosilane may be used. By providingthe protective film, it is possible to improve moisture resistance ofthe wire grid polarizer and to improve the reliability. Although theprotective film can be formed by various CVD methods, a coating method,various PVD methods including a sputtering method and a vacuumevaporation method, and a known process such as a sol-gel method, it ispreferable to employ a so-called Atomic Layer Deposition (ALD) method ora high-density plasma chemical vapor deposition (HDP-CVD) method. Byemploying the ALD method or the HDP-CVD method, it is possible to form athin protective film conformally on the wire grid polarizer. Althoughthe protective film may be formed on the entire surface of the wire gridpolarizer, it is also possible that the protective film is formed onlyon the side surface of the wire grid polarizer but is not formed on abase insulating layer positioned between wire grid polarizers. Byforming the protective film so as to cover the side surface which is anexposed portion of the metal material or the like constituting the wiregrid polarizer, it is possible to block moisture and an organic materialin the air and to reliably suppress the occurrence of corrosion of themetal material or the like constituting the wire grid polarizer and theoccurrence of a problem of abnormal precipitation. Moreover, it ispossible to achieve an improvement of long-term reliability of theimaging element and to provide an imaging element having an on-chip wiregrid polarizer having higher reliability.

According to the embodiments of the present disclosure, each imagingelement constituting the imaging device may have a wire grid polarizer,or a part of the imaging elements may have the wire grid polarizer. Theimaging element unit including a plurality of imaging elements may havea Bayer arrangement, and one imaging element unit (one pixel) may bemade up of four imaging elements. The arrangement of the imaging elementunits is not limited to the Bayer arrangement, and examples of thearrangement include an interline arrangement, a G-striped RB-checkeredarrangement, a G-striped and RB-complete-checkered arrangement, acheckered complementary-color arrangement, a stripe arrangement, anoblique-stripe arrangement, a primary-color color-differencearrangement, a field color-difference sequence arrangement, a framecolor-difference sequence arrangement, a MOS arrangement, a modified MOSarrangement, a frame interleaved arrangement, and a field interleavedarrangement. For example, in the case of the Bayer arrangement, each ofred, green, and blue color filter layers is disposed in each of threesubpixel areas in 2×2 subpixel areas. A color filter layer is notdisposed in the remaining one subpixel area in which a green colorfilter layer ought to be disposed in general, and a wire grid polarizeris disposed in the remaining one subpixel area. Alternatively, in thecase of the Bayer arrangement, each of red, green, and blue color filterlayers is disposed in each of three subpixel areas in 2×2 subpixelareas, and a green color filter layer and a wire grid polarizer aredisposed in the remaining one subpixel area. Sometimes the filer is notnecessary in the case where color separation or spectroscopy is notintended, or in the case of an imaging element having sensitivity to aspecific wavelength. In the subpixel area in which the color filterlayer is not disposed, a transparent resin layer may be disposed insteadof the color filter layer in order to secure flatness between thissubpixel area and subpixel areas in which color filter layers aredisposed. That is, the imaging element may constitute a combination ofthe red imaging element having sensitivity to red, the green imagingelement having sensitivity to green, and the blue imaging element havingsensitivity to blue. In addition, the imaging element may constitute acombination of infrared imaging elements having sensitivity to infrared,may be an imaging device that obtains a monochrome image, or may be animaging device that obtains a combination of a monochrome image and aninfrared image.

The imaging element or the like according to the embodiments of thepresent disclosure may be a CCD, a CMOS image sensor, a contact imagesensor (CIS), or a charge modulation device (CMD) type signalamplification image sensor. Moreover, the imaging element may be afront-illuminated imaging element or a back-illuminated imaging element.By using the imaging device, a digital still camera, a video camera, acamcorder, a security camera, a car-mounted camera, a smartphone camera,a game user interface camera, or a biometric authentication camera canbe formed, for example. In addition to normal image capturing, theimaging device can acquire polarization information at the same time. Inaddition, the imaging device may capture a stereoscopic image.

First Embodiment

The first embodiment relates to an imaging element, a method ofmanufacturing the imaging element, an imaging device, and a method ofmanufacturing the imaging device according to an embodiment of thepresent disclosure. More specifically, the first embodiment relates tothe imaging element A according to the embodiment of the presentdisclosure. In the first embodiment, the wire grid polarizer is disposedabove the on-chip lens (OCL). The imaging device includes theback-illuminated imaging element. FIG. 1 and FIG. 2 each illustrate aschematic partial end view of the imaging elements constituting theimaging device according to the first embodiment. FIG. 3 and FIG. 4 eachillustrate a schematic partial plan view of the imaging elements in theimaging device according to the first embodiment. FIG. 5 illustrates aschematic perspective view of the wire grid polarizer constituting theimaging element in the imaging device according to the first embodiment.FIG. 6 illustrates a schematic plan view of the imaging device showingthe imaging area and the like in the imaging device according to thefirst embodiment. FIG. 1 and FIG. 2 each illustrate two imagingelements, and FIG. 3 and FIG. 4 each illustrate four imaging elements.In addition, FIG. 1 is the schematic partial end view along arrows A-Ain FIG. 3 and FIG. 4, and FIG. 2 is the schematic partial end view alongarrows B-B in FIG. 3 and FIG. 4. FIG. 1 and FIG. 2 illustrate theschematic partial end view of the imaging elements in the direction inwhich the band-like light-reflecting layer extends in the wire gridpolarizers, and the schematic partial end view of the imaging elementsin the repeating direction of the band-like light-reflecting layer(direction perpendicular to the direction in which the band-likelight-reflecting layer extends). In FIG. 3 and FIG. 4, boundariesbetween imaging elements are illustrated with dotted lines, and gaps(spaces) between the stacked structures are hatched.

An imaging element 21 in the first embodiment includes:

a photoelectric conversion unit 40 on a substrate 31; and

a wire grid polarizer 50 which is arranged at a light-incident side ofthe photoelectric conversion unit 40 and in which a plurality of stackedstructures 54 are separately placed side by side, each of the stackedstructures 54 including at least a band-like light-reflecting layer 51and a band-like light-absorbing layer 53.

The light-reflecting layer 51 is made of a first electrical conductingmaterial (specifically, aluminum (Al)).

The light-absorbing layer 53 is made of a second electrical conductingmaterial (specifically, tungsten (W)).

An extending part 51 a of the light-reflecting layer 51 is electricallyconnected to the substrate 31 or the photoelectric conversion unit 40photoelectric conversion unit 40 in first embodiment. More specifically,the extending part 51 a of the light-reflecting layer 51 is electricallyconnected to the light-blocking layer 47. In at least one example, thelight-blocking layer 47 is grounded.

The imaging device according to the first embodiment includes aplurality of the imaging elements 21 according to the first embodimentin an imaging area 11. For example, the imaging device includes two ormore kinds of wire grid polarizers 50 having polarization directionsdifferent from each other, for example. An extending part 51 a of thelight-reflecting layer 51 is electrically connected to the substrate 31or the photoelectric conversion unit 40 (photoelectric conversion unit40 in first embodiment. More specifically, light-blocking layer 47). Atransmission axis of a wire grid polarizer 50A in an imaging element 21Ais perpendicular to a transmission axis of a wire grid polarizer 50B inan adjacent imaging element 21B. By using the imaging device accordingto the first embodiment, a digital still camera, a video camera, acamcorder, a security camera, a car-mounted camera (car camera), asmartphone camera, a game user interface camera, or a biometricauthentication camera can be formed, for example. In the firstembodiment, an on-chip lens 44 is disposed above a photoelectricconversion area 41, and the wire grid polarizer 50 is disposed above theon-chip lens 44. A reference sign 22 indicates an area occupied by theimaging element 21, and a reference sign 23 indicates an area betweenthe imaging elements 21.

In the first embodiment, an area in which the photoelectric conversionunit 40 is electrically connected to a light-reflecting layer-forminglayer 51A is positioned in the imaging area 11. In other words, the areain which the extending part 51 a of the light-reflecting layer 51 iselectrically connected to the photoelectric conversion unit 40 ispositioned in the imaging area 11. The area in which the photoelectricconversion unit 40 is electrically connected to a light-reflectinglayer-forming layer 51A or the extending part 51 a of thelight-reflecting layer 51 may be provided in each imaging element, ormay be provided for one of a plurality of imaging elements, or for oneof all the imaging elements.

Specifically, in the imaging element 21 according to the firstembodiment, the photoelectric conversion area 41, a first planarizingfilm 42, a wavelength selection layer (color filter layer 43), theon-chip lens 44, a planarizing layer (referred to as second planarizingfilm 45), a base insulating layer 46, and the wire grid polarizer 50 arestacked in this order. The photoelectric conversion area 41 is in thesubstrate 31 including a silicon semiconductor substrate. The firstplanarizing film 42 and the base insulating layer 46 are made of SiO₂,and the planarizing layer (second planarizing film 45) is made ofacrylic resin. The photoelectric conversion area 41 includes the CCD,the CMOS image sensor, or the like. For example, the light-blockinglayer (so-called black matrix layer) 47 made of tungsten (W) or the likeis positioned above an area between the adjacent on-chip lenses 44 (morespecifically, is positioned in base insulating layer 46 above a boundarybetween the on-chip lenses 44). The light-blocking layer 47 ispreferably positioned in the base insulating layer 46 that is insulatingmaterial, so as to avoid mutual interference of free electrons in thelight-blocking layer 47 and the light-reflecting layer 51 made of metalmaterial, for example.

In the imaging element according to the first embodiment, thephotoelectric conversion unit 40 includes the photoelectric conversionarea 41, the first planarizing film 42, the wavelength selection layer(color filter layer 43), the on-chip lens 44, the planarizing layer(second planarizing film 45), the base insulating layer 46, and thelight-blocking layer 47.

In the imaging device according to the first embodiment, thelight-reflecting layer 51 and the light-absorbing layer 53(specifically, light-reflecting layer 51, insulating layer 52, andlight-absorbing layer 53 in first embodiment) are shared by the imagingelements. That is, the area 23 between the imaging elements, an opticalblack pixel area (OPB) 12, and a peripheral area 13 are occupied by asecond stacked structure (frame) 26 including the light-reflecting layer51, the insulating layer 52, and the light-absorbing layer 53. Gaps(spaces) 55 are in between the stacked structures 54. In other words,the stacked structures 54 have the line and space pattern.

The light-blocking layer 47 is in the area 23 between the imagingelements, and the extending part 51 a of the light-reflecting layer 51is in contact with the area of the light-blocking layer 47. Forconvenience, in FIG. 4, a part in which the extending part 51 a of thelight-reflecting layer 51 is in contact with the area if thelight-blocking layer 47 is boxed and denoted with a reference sign “A”.The length of the extending part 51 a of the light-reflecting layer 51in contact with the area of the light-blocking layer 47 is the same asthe length of the photoelectric conversion area 41. Such configurationscan prevent color mixture from neighboring imaging elements. The area inwhich the light-reflecting layer 51 (light-reflecting layer-forminglayer 51A) is in contact with the light-absorbing layer 53(light-absorbing layer-forming layer 53A) is the area 23 between theimaging elements, and is at least one (specifically, four) of the fourcorners of the imaging element. For convenience, in FIG. 4, the area inwhich the light-reflecting layer 51 (light-reflecting layer-forminglayer 51A) is in contact with the light-absorbing layer 53(light-absorbing layer-forming layer 53A) is boxed and denoted with areference sign “B”. To simplify the drawings, positions of the extendingpart 51 a (light-reflecting layer extending part 51A) of thelight-reflecting layer 51 and the extending part 53 a of thelight-absorbing layer-forming layer 53A in FIGS. 1 and 2 or FIGS. 8 and9 are discrepant from positions of the extending parts 51 a and 53 a inFIG. 4. In some cases, the part A in which the extending part 51 a ofthe light-reflecting layer 51 is in contact with the area of thelight-blocking layer 47 may surround the imaging element, and the area Bin which the light-reflecting layer 51 (light-reflecting layer-forminglayer 51A) is in contact with the light-absorbing layer 53(light-absorbing layer-forming layer 53A) may surround the imagingelement.

In the first embodiment, the imaging element unit (pixel) 24 made of aplurality of imaging elements has the Bayer arrangement, and constitutesfour imaging elements. FIG. 10 illustrates a conceptual diagram of suchimaging element units 24 having the Bayer arrangement. The one imagingelement unit (one pixel) 24 is made of one subpixel that receives redlight (red imaging element R in FIG. 10), one subpixel that receivesblue light (blue imaging element B in FIG. 10), and two subpixels thatreceive green light (green imaging elements G in FIG. 10). The imagingelement units 24 are arranged in a two-dimensional matrix form in a rowdirection and a column direction. The first directions of all the wiregrid polarizers 50 in one imaging element unit are the same. Inaddition, the first directions of the wire grid polarizers 50 in imagingelement units arranged in the row direction are the same. On the otherhand, an imaging element unit in which the first direction of the wiregrid polarizers 50 is parallel to the row direction and an imagingelement unit in which the first direction of the wire grid polarizers 50is parallel to the column direction are arranged alternately in thecolumn direction. In FIG. 10 and FIGS. 11 to 24 to be described later,wire grid polarizers are hatched.

As described above, in the wire grid polarizer 50, the light-reflectinglayer 51, the insulating layer 52, and the light-absorbing layer 53 arestacked in this order from the photoelectric conversion unit 40 side. Inother words, the stacked structure 54 includes the light-reflectinglayer 51, the insulating layer 52, and the light-absorbing layer 53. Inaddition, the insulating layer 52 is on a whole top surface of thelight-reflecting layer 51, and the light-absorbing layer 53 is on awhole top surface of the insulating layer 52. Specifically, thelight-reflecting layer 51 is made of aluminum (Al) having the thicknessof 150 nm, the insulating layer 52 is made of SiO₂ having the thicknessof 25 nm or 50 nm, and the light-absorbing layer 53 is made of tungsten(W) having the thickness of 25 nm. Although the base film made of Ti,TiN, or a stacked structure of Ti/TiN is in between the photoelectricconversion unit 40 and the light-reflecting layer 51, the base film isomitted in the drawings. The direction in which the band-likelight-reflecting layer 51 extends (first direction) is identical to thepolarization orientation in which light is extinguished, and therepeating direction of the band-like light-reflecting layer 51 (seconddirection perpendicular to first direction) is identical to thepolarization orientation in which light penetrates. In other words, thelight-reflecting layer 51 has a function of a polarizer. Among lightincident on the wire grid polarizer 50, the light-reflecting layer 51attenuates polarized waves having an electric field component in adirection parallel to the direction in which the light-reflecting layerextends (first direction), and the light-reflecting layer 51 transmitspolarized waves having an electric field component in a directionperpendicular to the direction in which the light-reflecting layer 51extends (second direction). The first direction is the light-absorbingaxis of the wire grid polarizer 50, and the second direction is thelight transmission axis of the wire grid polarizer 50.

In the first embodiment, the length of the stacked structure 54 in thefirst direction is the same as the length in the first direction of thephotoelectric conversion area 41 in the first direction. In the examplein the drawings, imaging elements having an angle of 0 degree andimaging elements having an angle of 90 degrees between the firstdirection (direction in which band-like light-reflecting layer 51extends) and a direction in which a plurality of imaging elements arearranged are combined. However, imaging elements having an angle of 0degree, imaging elements having an angle of 45 degrees, imaging elementshaving an angle of 90 degrees, and imaging elements having an angle of135 degrees between the first direction (direction in which band-likelight-reflecting layer 51 extends) and the direction in which aplurality of imaging elements are arranged may be combined.

Hereinafter, with reference to FIG. 7A, FIG. 7B, FIG. 7C, and FIG. 7Dthat are each a schematic partial end view of a substrate and the like,the methods of manufacturing an imaging element and an imaging deviceaccording to the first embodiment will be described.

<Step 100>

First, on the basis of a known method, various kinds of driving circuitsand wiring (wiring layer) to drive the imaging element are formed on onesurface of the substrate 31 made of a silicon semiconductor substrate.Reference signs 32 indicate the driving circuit and wiring (wiringlayer) as a whole. Next, the other surface of the substrate 31 is groundand/or thinned to obtain the substrate 31 having a desired thickness. Areference sign 33 indicates an interlayer insulating film on the onesurface of the substrate 31.

<Step 110>

Subsequently, the photoelectric conversion unit 40 is formed on thesubstrate 31 on the basis of a known method. In other words, accordingto the known method, the photoelectric conversion area 41 is formed onthe other surface of the substrate 31, and a connection part (notillustrated) for electrically connecting the photoelectric conversionarea 41 and the driving circuit and wiring (wiring layer) 32 is formed.Next, the first planarizing film 42, the wavelength selection layer(color filter layer 43), the on-chip lens 44, the planarizing layer(second planarizing film 45), the light-blocking layer 47, and the baseinsulating layer 46 are formed on the photoelectric conversion area 41according to known methods. Thereby, the photoelectric conversion unit40 is prepared. As described above, the photoelectric conversion unit 40includes the photoelectric conversion area 41, the first planarizingfilm 42, the wavelength selection layer (color filter layer 43), theon-chip lens 44, the planarizing layer (second planarizing film 45), thelight-blocking layer 47, and the base insulating layer 46. The baseinsulating layer 46 has a first opening 46B above the light-blockinglayer 47.

<Step 120>

Next, the base film (not illustrated) made of Ti, TiN, or the stackedstructure of Ti/TiN, and the light-reflecting layer-forming layer 51made of the first electrical conducting material (specifically,aluminum) are formed above the photoelectric conversion unit 40(specifically, above base insulating layer 46) on the basis of thevacuum evaporation method (see FIG. 7A and FIG. 7B). Thelight-reflecting layer-forming layer 51A extends to the top surface ofthe light-blocking layer 47 through the first opening 46B. In otherwords, the light-reflecting layer-forming layer 51A made of the firstelectrical conducting material is electrically connected to thesubstrate 31 or the photoelectric conversion unit 40 (specifically,light-blocking layer 47 in first embodiment). This means that thelight-reflecting layer-forming layer 51A which is made of the firstelectrical conducting material and which is electrically connected tothe substrate 31 or the photoelectric conversion unit 40 is formed onthe photoelectric conversion unit 40. A reference sign 51 a indicates apart of the light-reflecting layer-forming layer 51A connected to thelight-blocking layer 47.

<Step 130>

Next, on or above the light-reflecting layer-forming layer 51A, thelight-absorbing layer-forming layer 53A which is made of the secondelectrical conducting material and at least a part of which is incontact with the light-reflecting layer-forming layer 51A is formed.Specifically, an insulating layer-forming layer 52A made of SiO₂ isformed on the light-reflecting layer-forming layer 51A on the basis ofthe CVD method. Subsequently, on the basis of the photolithographytechnology and the etching technology, a second opening 52B is formed ina part of the insulating-layer forming layer 52A positioned above adesired area in the light-reflecting layer-forming layer 51A where thestacked structure 54 is to be formed. Thereby, the structure illustratedin FIG. 7C can be obtained. Subsequently, the light-absorbinglayer-forming layer 53A made of tungsten (W) is formed on theinsulating-layer forming layer 52A including inside of the secondopening 52B, according to the sputtering method. Thereby, the structureillustrated in FIG. 7D can be obtained. The light-reflectinglayer-forming layer 51A and the light-absorbing layer-forming layer 53Aare connected via the extending part 53 a of the light-absorbinglayer-forming layer 53A extending through the second opening 52B. Inthis step, the light-absorbing layer-forming layer 53A is formed in astate in which potential of the light-reflecting layer-forming layer 51Ais set to a predetermined potential via the substrate 31 or thephotoelectric conversion unit 40 (specifically, in a state in whichlight-reflecting layer-forming layer 51A is grounded via light-blockinglayer 47 in the first embodiment).

<Step 140>

Subsequently, the light-absorbing layer-forming layer 53A, theinsulating-layer forming layer 52A, the light-reflecting layer-forminglayer 51A, and the base film are patterned on the basis of thelithography technology and the dry etching technology to obtain the wiregrid polarizer 50 in which the plurality of stacked structures 54 areseparately placed side by side, each of the stacked structures 54including the band-like light-reflecting layer, insulating layer 52, andlight-absorbing layer 53. In this step, the light-absorbinglayer-forming layer 53A, the insulating layer-forming layer 52A, and thelight-reflecting layer-forming layer 51A are patterned in a state inwhich potential of the light-reflecting layer-forming layer 51A is setto a predetermined potential via the substrate 31 or the photoelectricconversion unit 40 (specifically, in a state in which light-reflectinglayer-forming layer 51A is grounded via light-blocking layer 47 in thefirst embodiment). The area 23 between the imaging elements, the opticalblack pixel area (OPB) 12, and the peripheral area 13 are occupied bythe second stacked structure (frame) 56 including the light-reflectinglayer 51, the insulating layer 52, and the light-absorbing layer 53.After that, a protective film which is made of insulating material suchas SiO₂, SiON, SiN, or the like and has a thickness of several tens ofnm (specifically, protective film having thickness of 15 nm on sidesurface of wire grid polarizer 50, for example) may be formedconformally on the entire surface based on the HDP-CVD method or the ALDmethod as necessary.

<Step 150>

After that, the imaging device may be assembled based on a known methodwhich involves formation of electrode pads (not illustrated), dicing forchip separation, and packaging.

In the imaging element according to the first embodiment, thelight-reflecting layer-forming layer is electrically connected to thephotoelectric conversion unit, the light-reflecting layer-forming layerelectrically connected to the photoelectric conversion unit is prepared,and the extending part of the light-reflecting layer is electricallyconnected to the photoelectric conversion unit. Therefore, duringformation of the wire grid polarizer, it is certainly possible toprevent the wire grid polarizer and the photoelectric conversion unitfrom being damaged after the light-reflecting layer-forming layer or thelight-absorbing layer-forming layer is charged and a kind of dischargeoccurs.

In addition, since the wire grid polarizers are integrally formed abovethe photoelectric conversion areas in an on-chip form, it is possible todecrease the thickness of the imaging element. As a result, it ispossible to minimize mixing (polarization crosstalk) of polarized lightinto the adjacent imaging element. Moreover, since the wire gridpolarizer is an absorption-type wire grid polarizer having an absorptionlayer, reflectance is low, and the influence of stray light, flare, orthe like on video can be reduced.

In addition, since the imaging device includes the wire grid polarizers,the imaging device can acquire polarization information and a normalcaptured image at the same time. In other words, the imaging device hasa polarization separation function to spatially separate polarizationinformation of incident light. Specifically, each imaging element canobtain light intensity, polarization component intensity, and apolarization direction. Therefore, for example, image data can beprocessed on the basis of polarization information after capturing animage. For example, by performing a desired process on a part of animage capturing sky or a glass window, a part of an image capturing awater surface, or the like, it is possible to emphasize or understate apolarization component, to separate the polarization component and anon-polarization component, to improve contrast of an image, or todelete unnecessary information. Specifically, such a process can becarried out by setting an image capturing mode when an image is capturedby using the imaging device, for example. In addition, the imagingdevice can delete reflection from a glass window, and can sharpenboundaries (outline) of a plurality of objects by adding polarizationinformation to image information. In addition, it is also possible todetect a status of a road surface and to detect obstacles on the road.It is also possible to capture an image of a pattern reflecting abirefringent property of an object, to measure retardation distribution,to acquire a polarization microscope image, to acquire a surface shapeof the object, to measure a surface texture of the object, to detect amoving object (car and the like), and to carry out weather observationfor measuring cloud distribution. As described, application or adoptionto various kinds of fields is possible. In addition, the imaging devicemay calculate normal lines on the basis of polarization information, andintegrate them to capture a stereoscopic image.

Instead of electrically connecting the light-reflecting layer-forminglayer 51A to the photoelectric conversion unit 40, the light-reflectinglayer-forming layer 51A may be electrically connected to the substrate31 (for example, driving circuit, wiring, wiring layer 32). The area inwhich the substrate 31 or the photoelectric conversion unit 40 iselectrically connected to the light-reflecting layer-forming layer 51Amay be positioned in the optical black pixel area (OPB) 12 at the outercircumference of the imaging area 11 or may be positioned in theperipheral area 13 outside the imaging area 11. The light-blocking layeris also formed in the peripheral area 13, and the extending part 51 a ofthe light-reflecting layer 51 is in contact with the area of thelight-blocking layer. The length of the extending part of thelight-reflecting layer in contact with the area of the light-blockinglayer can be an arbitrary length inherently. For convenience, in theright side of FIG. 6, parts in which the extending part 51 a of thelight-reflecting layer 51 is in contact with the area of thelight-blocking layer 47 are boxed and denoted with a reference sign “A”.In addition, for convenience, in FIG. 6, the areas in which thelight-reflecting layer 51 (light-reflecting layer-forming layer 51A) isin contact with the light-absorbing layer 53 (light-absorbinglayer-forming layer 53A) are boxed and denoted with a reference sign“B.” FIG. 6 illustrates only a part of the areas A and B. Alternatively,although dicing is carried out to cut off chips, sometimes the area inwhich the substrate 31 or the photoelectric conversion unit 40 iselectrically connected to the light-reflecting layer-forming layer 51Amay be positioned in a scribe part between imaging devices.

The wire grid polarizer may have a structure in which the insulatinglayer is omitted. In other words, in the wire grid polarizer, thelight-reflecting layer (made of aluminum, for example) and thelight-absorbing layer (made of tungsten, for example) are stacked inthis order from the photoelectric conversion unit 40 side.Alternatively, the wire grid polarizer may include a single-layerconductor light-blocking material layer. Examples of materialconstituting the conductor light-blocking material layer includesconductor material having a small complex refraction index in awavelength band to which the imaging element has sensitivity, such asaluminum (Al), copper (Cu), gold (Au), silver (Ag), platinum (Pt),tungsten (W), or an alloy including such metal.

Second Embodiment

The second embodiment is a modification of the first embodiment, andrelates to the imaging element B according to an embodiment of thepresent disclosure. In this embodiment, the on-chip lens (OCL) isdisposed above the wire grid polarizer. The wavelength selection layer(specifically, for example, a known color filter layer) is disposedbetween the wire grid polarizer (positioned at lower side) and theon-chip lens (positioned at upper side).

Specifically, in the second embodiment, FIG. 8 and FIG. 9 eachillustrate the schematic partial end view of the imaging element. Theplanarizing layer 45 and the base insulating layer 46 are formed abovethe photoelectric conversion area (light-receiving area) 41, and thewire grid polarizer 50 is formed on the base insulating layer 46. Inaddition, the third planarizing film 48 (wire grid polarizer embeddedmaterial layer), the wavelength selection layer (color filter layer 43),and the on-chip lens 44 are formed above the wire grid polarizer 50. Thephotoelectric conversion unit 40 includes the photoelectric conversionarea (light-receiving area) 41, the planarizing layer 45, and the baseinsulating layer 46. The light-blocking layer 47 is on the planarizinglayer 45, and the first opening 46B is formed in a part of the baseinsulating layer 46 positioned above the light-blocking layer 47. Thethird planarizing film 48 is made of SiO₂, acrylic resin, SOG, or thelike. The arrangement of imaging elements is the Bayer arrangement alsoin the second embodiment. FIG. 8 is the schematic partial end viewsimilar to the drawing along arrows A-A in FIGS. 3 and 4, and FIG. 9 isthe schematic partial end view similar to the drawing along arrows B-Bin FIGS. 3 and 4.

In the second embodiment, the wire grid polarizer is in between thephotoelectric conversion area 41 and the on-chip lens 44, and is closerto the substrate side than the wavelength selection layer (specifically,color filter layer 43). Therefore, the wire grid polarizer 50 is formedbefore formation of the color filter layer, and a processing temperatureis nearly unlimited. In addition, the wire grid polarizer 50 is embeddedin the third planarizing film 48. Accordingly, it is possible to surelyprevent damage to the wire grid polarizer due to dicing for cutting offchips when the imaging device is mounted on a package. In addition,since the wire grid polarizer 50 is positioned near the photoelectricconversion area 41, leakage of light into adjacent imaging elements(polarization crosstalk) can be prevented.

While preferred embodiments of the present disclosure have beendescribed, the present disclosure is not limited to these embodiments.The configuration and structure of the wire grid polarizer, the imagingelement, and the imaging device described in the embodiments areexemplary, and can be changed appropriately. The methods ofmanufacturing thereof are also exemplary, and can be changedappropriately. Instead of the back-illuminated imaging element, theimaging element may be a front-illuminated imaging element.Specifically, for example, in the imaging element, the photoelectricconversion area 41 in the silicon semiconductor substrate, the firstplanarizing film 42, the wavelength selection layer (color filter layer)43, the on-chip lens 44, the planarizing layer (second planarizing film)45, the light-blocking layer 47, the base insulating layer 46, and thewire grid polarizer 50 are stacked in this order. Alternatively, in theimaging element, the photoelectric conversion area 41 in the siliconsemiconductor substrate, the planarizing layer 45, the light-blockinglayer 47, the base insulating layer 46, and the wire grid polarizer 50,the third planarizing film 48, the wavelength selection layer (colorfilter layer) 43, and the on-chip lens 44 are stacked in this order.

In the embodiments, the wire grid polarizer is used mainly for acquiringpolarization information in the imaging element having sensitivity to avisible light wavelength band. However, in the case where the imagingelement has sensitivity to infrared or ultraviolet light, a wire gridpolarizer functioning in an arbitrary wavelength band can be mounted byenlarging/reducing the pitch P₀ at which the stacked structure has beenformed according to the sensitivity of the imaging element. In addition,a wire grid polarizer may be embodied as the disclosure alone when theplurality of stacked structures are separately placed side by side inthe wire grid polarizer, the light-reflecting layer, the insulatinglayer, and the light-absorbing layer are stacked in this order in eachof the stacked structures from the photoelectric conversion unit side,the insulating layer is on the whole top surface of the light-reflectinglayer, and the light-absorbing layer is on the whole top surface of theinsulating layer.

The arrangement state of the imaging elements in the imaging elementunit having the Bayer arrangement is not limited to FIG. 10. In theplanner layout of the imaging element units in FIGS. 11 to 24 to bedescribed below, “R” represents a red imaging element having a red colorfilter layer, “G” represents a green imaging element having a greencolor filter layer, “B” represents a blue imaging element having a bluecolor filter layer, and “W” represents a white imaging element having nocolor filter layer.

As illustrated in FIG. 11, for example, imaging elements having an angleof 45 degrees between the first direction and a direction in which aplurality of imaging elements are arranged, and imaging elements havingan angle of 135 degrees between the first direction and the direction inwhich a plurality of imaging elements are arranged can be combined.

In the example in FIG. 12, the red imaging elements R, the green imagingelements G, and the blue imaging elements B do not have the wire gridpolarizer 50, and the white imaging elements W have the wire gridpolarizers 50. In FIG. 12, the white imaging elements W each having thewire grid polarizer 50 are disposed at every other imaging element in anX direction and a Y direction. However, the white imaging elements W maybe disposed at every two or three imaging elements, or the imagingelements each having the wire grid polarizer 50 may be disposed in ahoundstooth pattern.

As illustrated in the planer layout in FIG. 13, the arrangement of thecolor filter layers may be basically the Bayer arrangement. The red,green, and blue color filter layers may be disposed in one imagingelement unit (one pixel) made of four (2×2) imaging elements. Oneimaging-element-unit group may be made of four imaging element units,and the wire grid polarizer may be disposed in one of the four imagingelements constituting each imaging element unit.

It is also possible to use a configuration illustrated in the planerlayout in FIG. 14 or FIG. 15. In the case of a CMOS image sensor havingthe planer layout in FIG. 14, a 2×2 pixels sharing method in which aselection transistor, a reset transistor, and an amplificationtransistor are shared by 2×2 imaging elements can be used. An imageincluding polarization information is captured in an image capturingmode in which pixel summation is not performed, and a normally capturedimage in which all polarization components are integrated is provided ina mode in which FD addition of accumulated charge in 2×2 subpixel areasis performed. In the case of the planer layout in FIG. 15, the wire gridpolarizers are disposed in one direction in 2×2 imaging elements.Therefore, it is difficult to form discontinuous stacked structuresbetween the imaging element units, and high-quality polarization imagingcan be carried out.

It is also possible to use a configuration illustrated in the planerlayout in FIG. 16, FIG. 17, FIG. 18, FIG. 19, FIG. 20, FIG. 21, FIG. 22,FIG. 23, and FIG. 24.

It should be understood by those skilled in the art that variousmodifications, combinations, sub-combinations, and alterations may occurdepending on design requirements and other factors insofar as they arewithin the scope of the appended claims or the equivalents thereof.

Additionally, the present technology may also be configured as below.

(A01) <<Method of Manufacturing Imaging Device>>

A method of manufacturing an imaging device including a plurality ofimaging elements in an imaging area,

each of the imaging elements including

a photoelectric conversion unit on a substrate, and

a wire grid polarizer which is arranged at a light-incident side of thephotoelectric conversion unit and in which a plurality of stackedstructures are separately placed side by side, each of the stackedstructures including at least a band-like light-reflecting layer and aband-like light-absorbing layer,

the method including:

manufacturing each of the imaging elements by

(a) forming a light-reflecting layer-forming layer made of a firstelectrical conducting material on the photoelectric conversion unitafter forming the photoelectric conversion unit,

(b) next, on or above the light-reflecting layer-forming layer, forminga light-absorbing layer-forming layer which is made of a secondelectrical conducting material and at least a part of which is incontact with the light-reflecting layer-forming layer, and

(c) subsequently, patterning the light-absorbing layer-forming layer andthe light-reflecting layer-forming layer to obtain the wire gridpolarizer in which the plurality of stacked structures are separatelyplaced side by side, each of the stacked structures including theband-like light-reflecting layer and the band-like light-absorbinglayer, wherein, in (a), the light-reflecting layer-forming layer made ofthe first electrical conducting material is electrically connected tothe substrate or the photoelectric conversion unit.

(A02)

The method of manufacturing an imaging device according to (A01),wherein the light-reflecting layer and the light-absorbing layer areshared by the imaging elements.

(A03)

The method of manufacturing an imaging device according to (A01) or(A02), wherein in (b), the light-absorbing layer-forming layer made ofthe second electrical conducting material is formed on or above thelight-reflecting layer-forming layer in a state in which potential ofthe light-reflecting layer-forming layer is set to a predeterminedpotential via the substrate or the photoelectric conversion unit, and

in (c), the light-absorbing layer-forming layer and the light-reflectinglayer-forming layer are patterned in a state in which the potential ofthe light-reflecting layer-forming layer is set to a predeterminedpotential via the substrate or the photoelectric conversion unit.

(A04)

The method of manufacturing an imaging device according to any one of(A01) to (A03), wherein

an area in which the substrate or the photoelectric conversion unit iselectrically connected to the light-reflecting layer-forming layer ispositioned in the imaging area.

(A05)

The method of manufacturing an imaging device according to any one of(A01) to (A03), wherein

an area in which the substrate or the photoelectric conversion unit iselectrically connected to the light-reflecting layer-forming layer ispositioned in an optical black pixel area at an outer circumference ofthe imaging area.

(A06)

The method of manufacturing an imaging device according to any one of(A01) to (A03), wherein

an area in which the substrate or the photoelectric conversion unit iselectrically connected to the light-reflecting layer-forming layer ispositioned in a peripheral area outside the imaging area.

(A07)

The method of manufacturing an imaging device according to any one of(A01) to (A06), wherein

in the wire grid polarizer, the light-reflecting layer, an insulatinglayer, and the light-absorbing layer are stacked in this order from thephotoelectric conversion unit side.

(A08)

The method of manufacturing an imaging device according to (A07),wherein the insulating layer is formed on a whole top surface of thelight-reflecting layer, and the light-absorbing layer is formed on awhole top surface of the insulating layer.

(A09)

A method of manufacturing an imaging device including a plurality ofimaging elements in an imaging area, each imaging element including aphotoelectric conversion unit in a substrate and a wire grid polarizerarranged at a light-incident side of the photoelectric conversion unit,the method including:

forming the photoelectric conversion unit in the substrate;

forming a light-reflecting layer on or above the photoelectricconversion unit, wherein the light-reflecting layer includes a firstelectrical conducting material that is electrically connected to atleast one of the substrate or the photoelectric conversion unit;

forming a light-absorbing layer on or above the light-reflecting layer,wherein the light-absorbing layer includes a second electricalconducting material, and wherein at least a portion of thelight-absorbing layer is in contact with the light-reflecting layer; and

patterning the light-absorbing layer and the light-reflecting layer toform a wire grid polarizer including a plurality of stacked strip-shapedportions, wherein each of the plurality of stacked strip-shaped portionsincludes a portion of the light-reflecting layer and a portion of thelight-absorbing layer.

(A10)

The method of manufacturing an imaging device according to (A09),further including: forming an insulating layer on or above thelight-reflecting layer; and

forming an opening in the insulating layer, wherein the insulating layeris between the light light-reflecting layer and the light-absorbinglayer, and wherein each of the of the plurality of stacked strip-shapedportions includes the portion of the light-reflecting layer, a portionof the insulating layer, and the portion of the light-absorbing layer.

(A11)

The method of manufacturing an imaging device according to (A09) or(A10), further including:

setting a potential of the light-reflecting layer to a predeterminedpotential via the substrate or the photoelectric conversion unit; and

patterning the light-absorbing layer and the light-reflecting layer toform the wire grid polarizer while the potential of the light-reflectinglayer is set to the predetermined potential.

(A12)

The method of manufacturing an imaging device according to (A09),further including: forming an insulating layer on or above thephotoelectric conversion unit;

forming a light-blocking layer on the insulation layer; and

forming an opening in the insulating layer, wherein the light-reflectinglayer is in electrical contact with the light-blocking layer.

(A13)

The method of manufacturing an imaging device according to any one of(A09) to (A12), wherein an area in which the substrate or thephotoelectric conversion unit is electrically connected to thelight-reflecting layer is positioned in an imaging area of the imagingdevice.

(A14)

The method of manufacturing an imaging device according to any one of(A09) to (A13), wherein an area in which the substrate or thephotoelectric conversion unit is electrically connected to thelight-reflecting layer is positioned in an optical black pixel area atan outer circumference of an imaging area of the imaging device.

(A15)

The method of manufacturing an imaging device according to any one of(A09) to (A14), wherein an area in which the substrate or thephotoelectric conversion unit is electrically connected to thelight-reflecting layer is positioned in a peripheral area outside animaging area of imaging device.

(A16)

The method of manufacturing an imaging device according to any one of(A09) to (A15), wherein the light-reflecting layer and thelight-absorbing layer are shared by a plurality of imaging elements inthe imaging apparatus.

(A17)

The method of manufacturing an imaging device according to any one of(A09) to (A16), wherein the first electrical conducting materialincludes aluminum (AL) and the second electrical conducting materialincludes tungsten (W).

(A18)

The method of manufacturing an imaging device according to any one of(A09) to (A17), wherein the substrate is made of silicon (Si).

(A19)

The method of manufacturing an imaging element according to any one of(A09) to (A18), wherein the plurality of stacked strip-shaped portionsextends in a continuous manner above a plurality of photoelectricconversion units.

(B01) <<Method of Manufacturing Imaging Element>>

A method of manufacturing an imaging element including

a photoelectric conversion unit on a substrate, and

a wire grid polarizer which is arranged at a light-incident side of thephotoelectric conversion unit and in which a plurality of stackedstructures are separately placed side by side, each of the stackedstructures including at least a band-like light-reflecting layer and aband-like light-absorbing layer,

the method including:

(A) after forming the photoelectric conversion unit, forming alight-reflecting layer-forming layer which is made of a first electricalconducting material and which is electrically connected to the substrateor the photoelectric conversion unit, on the photoelectric conversionunit;

(B) next, on or above the light-reflecting-layer forming layer, forminga light-absorbing layer-forming layer which is made of a secondelectrical conducting material and at least a part of which is incontact with the light-reflecting layer-forming layer; and

(C) subsequently, patterning the light-absorbing layer-forming layer andthe light-reflecting layer-forming layer to obtain the wire gridpolarizer in which the plurality of stacked structures are separatelyplaced side by side, each of the stacked structures including theband-like light-reflecting layer and the band-like light-absorbinglayer.

(B02)

The method of manufacturing an imaging element according to (B01),wherein

in (B), the light-absorbing layer-forming layer made of the secondelectrical conducting material is formed on or above thelight-reflecting layer-forming layer in a state in which potential ofthe light-reflecting layer-forming layer is set to a predeterminedpotential via the substrate or the photoelectric conversion unit, and

in (C), the light-absorbing layer-forming layer and the light-reflectinglayer-forming layer are patterned in a state in which the potential ofthe light-reflecting layer-forming layer is set to a predeterminedpotential via the substrate or the photoelectric conversion unit.

(C01) <<Imaging Device>>

An imaging device including

a plurality of imaging elements in an imaging area,

each of the imaging elements including

a photoelectric conversion unit on a substrate, and

a wire grid polarizer which is arranged at a light-incident side of thephotoelectric conversion unit and in which a plurality of stackedstructures are separately placed side by side, each of the stackedstructures including at least a band-like light-reflecting layer and aband-like light-absorbing layer, wherein

the light-reflecting layer is made of a first electrical conductingmaterial,

the light-absorbing layer is made of a second electrical conductingmaterial, and

an extending part of the light-reflecting layer is electricallyconnected to the substrate or the photoelectric conversion unit.

(C02)

The imaging device according to (C01), wherein the light-reflectinglayer and the light-absorbing layer are shared by the imaging elements.

(C03)

The imaging device according to (C01) or (C02), wherein

an area in which the extending part of the light-reflecting layer iselectrically connected to the substrate or the photoelectric conversionunit is positioned in the imaging area.

(C04)

The imaging device according to (C01) or (C02), wherein

an area in which the extending part of the light-reflecting layer iselectrically connected to the substrate or the photoelectric conversionunit is positioned in an optical black pixel area at an outercircumference of the imaging area.

(C05)

The imaging device according to (C01) or (C02), wherein

an area in which the extending part of the light-reflecting layer iselectrically connected to the substrate or the photoelectric conversionunit is positioned in a peripheral area outside the imaging area.

(C06)

The imaging device according to any one of (C01) to (C05), wherein inthe wire grid polarizer, the light-reflecting layer, an insulatinglayer, and the light-absorbing layer are stacked in this order from thephotoelectric conversion unit side.

(C07)

The imaging device according to (C06), wherein

the insulating layer is on a whole top surface of the light-reflectinglayer, and the light-absorbing layer is on a whole top surface of theinsulating layer.

(C08)

The imaging device according to any one of (C01) to (C07), wherein

a base film is in between the photoelectric conversion unit and thelight-reflecting layer.

(C09)

An imaging device including:

a plurality of imaging elements in an imaging area, each imaging elementincluding:

a photoelectric conversion unit in a substrate;

a wire grid polarizer disposed at a light-incident side of thephotoelectric conversion unit, the wire grid polarizer including aplurality of stacked strip-shaped portions, each stacked strip-shapedportion including a light-reflecting layer and a light-absorbing layer;and

an extending portion of the light-reflecting layer electricallyconnected to the substrate or the photoelectric conversion unit,wherein, the light-reflecting layer includes a first electricalconducting material, and the light-absorbing layer includes a secondelectrical conducting material.

(D01) <<Imaging Element>>

An imaging element including:

a photoelectric conversion unit on a substrate; and

a wire grid polarizer which is arranged at a light-incident side of thephotoelectric conversion unit and in which a plurality of stackedstructures are separately placed side by side, each of the stackedstructures including at least a band-like light-reflecting layer and aband-like light-absorbing layer, wherein

the light-reflecting layer is made of a first electrical conductingmaterial,

the light-absorbing layer is made of a second electrical conductingmaterial, and an extending part of the light-reflecting layer iselectrically connected to the substrate or the photoelectric conversionunit.

(D02)

An imaging element including:

a photoelectric conversion unit in a substrate;

a wire grid polarizer disposed at a light-incident side of thephotoelectric conversion unit, the wire grid polarizer including aplurality of stacked strip-shaped portions, each stacked strip-shapedportion including a light-reflecting layer and a light-absorbing layer;and

an extending portion of the light-reflecting layer electricallyconnected to the substrate or the photoelectric conversion unit,wherein, the light-reflecting layer includes a first electricalconducting material, and the light-absorbing layer includes a secondelectrical conducting material.

(D03)

The imaging element according to (D02), further including:

an insulating layer formed on or above the light-reflecting layer; and

an opening in the insulating layer, wherein the insulating layer isbetween the light light-reflecting layer and the light-absorbing layer,and wherein each of the of the plurality of stacked strip-shapedportions includes the portion of the light-reflecting layer, a portionof the insulating layer, and the portion of the light-absorbing layer.

(D04)

The imaging element according to (D02) or (D03), wherein a potential ofthe light-reflecting layer is set to a predetermined potential via thesubstrate or the photoelectric conversion unit, and the light-absorbinglayer and the light-reflecting layer are patterned to form the wire gridpolarizer while the potential of the light-reflecting layer is set tothe predetermined potential.

(D05)

The imaging element according to (D02), further comprising:

an insulating layer formed on or above the photoelectric conversionunit;

a light-blocking layer formed on the insulation layer; and

an opening in the insulating layer, wherein the light-reflecting layeris in electrical contact with the light-blocking layer.

(D06)

The imaging element according to any one of (D02) to (D05), wherein anarea in which the substrate or the photoelectric conversion unit iselectrically connected to the light-reflecting layer is positioned in animaging area of the imaging element.

(D07)

The imaging element according to any one of (D02) to (D06), wherein anarea in which the substrate or the photoelectric conversion unit iselectrically connected to the light-reflecting layer is positioned in anoptical black pixel area at an outer circumference of an imaging area ofan imaging device.

(D08)

The imaging element according to any one of (D02) to (D07), wherein anarea in which the substrate or the photoelectric conversion unit iselectrically connected to the light-reflecting layer-forming layer ispositioned in a peripheral area outside an imaging area of an imagingdevice.

(D09)

The imaging element according to any one of (D02) to (D08), wherein thelight-reflecting layer and the light-absorbing layer are shared by aplurality of imaging elements in an imaging apparatus.

(E01) <<Imaging Device>>

An imaging device including

a plurality of imaging elements in an imaging area,

each of the imaging elements including

a photoelectric conversion unit on a substrate, and

a wire grid polarizer, wherein

in the wire grid polarizer, a plurality of band-like stacked structuresare separately placed side by side, each of the stacked structuresincluding the light-reflecting layer, an insulating layer, and thelight-absorbing layer in this order from the photoelectric conversionunit side, and

the insulating layer is formed on a whole top surface of thelight-reflecting layer, and the light-absorbing layer is formed on awhole top surface of the insulating layer.

(E02)

The imaging device according to (E01), wherein

the light-reflecting layer and the light-absorbing layer are shared bythe imaging elements.

(E03) <<Imaging Element>>

An imaging element including:

a photoelectric conversion unit on a substrate; and

a wire grid polarizer, wherein

in the wire grid polarizer, a plurality of band-like stacked structuresare separately placed side by side, each of the stacked structuresincluding the light-reflecting layer, an insulating layer, and thelight-absorbing layer in this order from the photoelectric conversionunit side, and

the insulating layer is formed on a whole top surface of thelight-reflecting layer, and the light-absorbing layer is formed on awhole top surface of the insulating layer.

REFERENCE SIGNS LIST

-   10 imaging device-   11 imaging area-   12 optical black pixel area (OPB)-   13 peripheral area-   21, 21A, 21B imaging element-   22 area occupied by imaging element-   23 area between imaging elements-   24 imaging element unit-   31 substrate-   32 driving circuit and wiring (wiring layer)-   33 interlayer insulating film-   40 photoelectric conversion unit-   41 photoelectric conversion area-   42 first planarizing film-   43 wavelength selection layer (color filter layer)-   44 on-chip lens-   45 planarizing layer (second planarizing film)-   46 base insulating layer-   46B first opening-   47 light-blocking layer-   48 third planarizing film-   50, 50A, 50B wire grid polarizer-   51 light-reflecting layer-   51A light-reflecting layer-forming layer-   51 a extending part of light-reflecting layer or light-reflecting    layer-forming layer-   52 insulating layer-   52A insulating layer-forming layer-   52B second opening-   53 light-absorbing layer-   53A light-absorbing layer-forming layer-   53 a extending part of light-absorbing layer or light-absorbing    layer-forming layer-   54 stacked structure-   55 gap (space) between stacked structures-   56 second stacked structure (frame)

1. A method of manufacturing an imaging device including a plurality ofimaging elements in an imaging area, each imaging element including aphotoelectric conversion unit in a substrate and a wire grid polarizerarranged at a light-incident side of the photoelectric conversion unit,the method comprising: forming the photoelectric conversion unit in thesubstrate; forming a light-reflecting layer on or above thephotoelectric conversion unit, wherein the light-reflecting layerincludes a first electrical conducting material that is electricallyconnected to at least one of the substrate or the photoelectricconversion unit; forming a light-absorbing layer on or above thelight-reflecting layer, wherein the light-absorbing layer includes asecond electrical conducting material, and wherein at least a portion ofthe light-absorbing layer is in contact with the light-reflecting layer;and patterning the light-absorbing layer and the light-reflecting layerto form the wire grid polarizer including a plurality of stackedstrip-shaped portions, wherein each of the plurality of stackedstrip-shaped portions includes a portion of the light-reflecting layerand a portion of the light-absorbing layer.
 2. The method ofmanufacturing an imaging device according to claim 1, furthercomprising: forming an insulating layer on or above the light-reflectinglayer; and forming an opening in the insulating layer, wherein theinsulating layer is between the light light-reflecting layer and thelight-absorbing layer, and wherein each of the of the plurality ofstacked strip-shaped portions includes the portion of thelight-reflecting layer, a portion of the insulating layer, and theportion of the light-absorbing layer.
 3. The method of manufacturing animaging device according to claim 1, further comprising: setting apotential of the light-reflecting layer to a predetermined potential viathe substrate or the photoelectric conversion unit; and patterning thelight-absorbing layer and the light-reflecting layer to form the wiregrid polarizer while the potential of the light-reflecting layer is setto the predetermined potential.
 4. The method of manufacturing animaging device according to claim 1, further comprising: forming aninsulating layer on or above the photoelectric conversion unit; forminga light-blocking layer on the insulation layer; and forming an openingin the insulating layer, wherein the light-reflecting layer is inelectrical contact with the light-blocking layer.
 5. The method ofmanufacturing an imaging device according to claim 1, wherein an area inwhich the substrate or the photoelectric conversion unit is electricallyconnected to the light-reflecting layer is positioned in an imaging areaof the imaging device.
 6. The method of manufacturing an imaging deviceaccording to claim 1, wherein an area in which the substrate or thephotoelectric conversion unit is electrically connected to thelight-reflecting layer is positioned in an optical black pixel area atan outer circumference of an imaging area of the imaging device.
 7. Themethod of manufacturing an imaging device according to claim 1, whereinan area in which the substrate or the photoelectric conversion unit iselectrically connected to the light-reflecting layer is positioned in aperipheral area outside an imaging area of the imaging device.
 8. Themethod of manufacturing an imaging device according to claim 1, whereinthe light-reflecting layer and the light-absorbing layer are shared by aplurality of imaging elements in the imaging device.
 9. The method ofmanufacturing an imaging device according to claim 1, wherein the firstelectrical conducting material includes aluminum (AL) and the secondelectrical conducting material includes tungsten (W).
 10. The method ofmanufacturing an imaging device according to claim 1, wherein thesubstrate is made of silicon (Si).
 11. The method of manufacturing animaging element according to claim 1, wherein the plurality of stackedstrip-shaped portions extends in a continuous manner above a pluralityof photoelectric conversion units.
 12. A method of manufacturing animaging device including a plurality of imaging elements in an imagingarea, each imaging element including a photoelectric conversion unit ina substrate and a wire grid polarizer arranged at a light-incident sideof the photoelectric conversion unit, the method comprising: forming thephotoelectric conversion unit in the substrate; forming alight-reflecting layer on or above the photoelectric conversion unit,wherein the light-reflecting layer includes a first electricalconducting material that is electrically connected to at least one ofthe substrate or the photoelectric conversion unit; forming alight-absorbing layer on or above the light-reflecting layer, whereinthe light-absorbing layer includes a second electrical conductingmaterial, and wherein at least a portion of the light-absorbing layer isin contact with the light-reflecting layer; patterning thelight-absorbing layer and the light-reflecting layer to form the wiregrid polarizer including a plurality of stacked strip-shaped portions,wherein each of the plurality of stacked strip-shaped portions includesa portion of the light-reflecting layer and a portion of thelight-absorbing layer; and forming an extending portion of thelight-reflecting layer which is electrically connected to the substrateor the photoelectric conversion unit.
 13. The method of manufacturing animaging device according to claim 12, further comprising electricallyconnecting the extending portion to a light-blocking layer, providedbetween the extending portion and the substrate and also disposedbetween the imaging element and a second imaging element that isadjacent to the imaging element.
 14. The method of manufacturing animaging device according to claim 13, further comprising: forming aninsulating layer on or above the light-reflecting layer; and forming anopening in the insulating layer, wherein the insulating layer is betweenthe light-reflecting layer and the light-absorbing layer, and whereineach of the of the plurality of stacked strip-shaped portions includesthe portion of the light-reflecting layer, a portion of the insulatinglayer, and the portion of the light-absorbing layer.
 15. The method ofmanufacturing an imaging device according to claim 12, furthercomprising: setting a potential of the light-reflecting layer to apredetermined potential via the substrate or the photoelectricconversion unit; and patterning the light-absorbing layer and thelight-reflecting layer to form the wire grid polarizer while thepotential of the light-reflecting layer is set to the predeterminedpotential.
 16. The method of manufacturing an imaging device accordingto claim 12, wherein an area in which the substrate or the photoelectricconversion unit is electrically connected to the light-reflecting layeris positioned in an imaging area of the imaging device.
 17. The methodof manufacturing an imaging device according to claim 12, wherein anarea in which the substrate or the photoelectric conversion unit iselectrically connected to the light-reflecting layer is positioned in anoptical black pixel area at an outer circumference of an imaging area ofthe imaging device.
 18. The method of manufacturing an imaging deviceaccording to claim 12, wherein an area in which the substrate or thephotoelectric conversion unit is electrically connected to thelight-reflecting layer is positioned in a peripheral area outside animaging area of the imaging device.
 19. The method of manufacturing animaging device according to claim 12, wherein the first electricalconducting material includes aluminum (AL) and the second electricalconducting material includes tungsten (W).
 20. The method ofmanufacturing an imaging device according to claim 12, wherein thesubstrate is made of silicon (Si).